Cells of the food borne pathogen E.coli 0157:H7 will be subjected to treatment with a newly-developed three-component natural antimicrobial system. This system has been designed to compromise the structural integrity of the Gram-negative outer membrane, allowing penetration to the cell membrane of certain membrane-active agents. We wish to use the HRSEM to visually evaluate the effects of all seven combinations of the system components on cellular ultrastructure relative to the control. This study will provide important data on the individual contributions of and interactions between the components of this antimicrobial system and will be invaluable in determining how the system inhibits this pathogen.